1. Field of the Invention
The present invention relates to a semiconductor light emitting element.
2. Description of the Related Art
Light emitting elements with a plurality of semiconductor layers, such as LEDs, have been proposed, for example, in JP 2011-54967 A, JP 2011-216524 A, and JP 2012-195321 A. For example, JP 2011-54967 A discloses an invention for improving light extraction efficiency by etching the upper face of a first semiconductor layer (first electrically-conductive semiconductor layer) to a predetermined depth so as to form a rough surface.
JP 2011-216524 A discloses an invention for allowing smooth current flow to an n-pad electrode by providing an auxiliary grid electrode that penetrates a second semiconductor layer (p-type layer), an active layer and a first semiconductor layer (n-type layer) so as to connect the auxiliary electrode to the n-pad electrode. JP 2012-195321 A discloses an invention for suppressing repetitive light reflection between the contact face of a first electrode and the upper face of the first semiconductor layer by smoothing the upper portion of the contact face between the first electrode and the first semiconductor layer in the upper face of the first semiconductor layer.
However, there are following disadvantages with the inventions disclosed in JP 2011-54967 A, JP 2011-216524 A, and JP 2012-195321 A. For example, in the invention disclosed in JP 2011-54967 A, the upper face of the first semiconductor layer is partly etched in the area above the contact between the first electrode and the first semiconductor layer, where electric current is likely to be concentrated. Therefore, in the invention disclosed in JP 2011-54967 A, current flow around the contact may be impeded to cause a rise in resistance, which may result in high drive voltage.
In the invention disclosed in JP 2011-216524 A, forming the auxiliary grid electrode decreases an area of the active layer by the amount thereof, which results in decreased light emission and decreased light extraction efficiency. In the invention disclosed in JP 2012-195321 A, because the area above the contact between the first electrode and the first semiconductor layer is flat, light may be reflected more into the laminate structure in this area due to its flat surface, which may result in decreased light extraction efficiency.